What an X-ray examination is

What an X-ray does

An X-ray examination uses a small, controlled burst of ionizing radiation to make a picture of the inside of the body. Tissues absorb the radiation differently: bone absorbs more and appears light, air-filled spaces absorb less and appear dark, and soft tissues fall in between. The result is a shadow image a clinician can read.

Plain X-rays are among the oldest and most common imaging tests. Typical uses include checking bones for fractures, looking at the lungs in chest infections, and examining teeth and joints.

What happens during the examination

The person is positioned so the body part of interest sits between the X-ray source and a detector. The exposure itself takes a fraction of a second and is painless; the whole visit usually takes a few minutes. Staying still during the exposure keeps the image sharp.

Some examinations use a contrast material, swallowed or injected, to make certain structures show up more clearly. Staff may ask about pregnancy before imaging, because developing pregnancies are more sensitive to radiation.

About the radiation dose

A plain X-ray delivers a small radiation dose, often comparable to days or a few months of the natural background radiation everyone receives from the environment. The clinical benefit of a well-chosen examination is expected to outweigh this small risk, and equipment and technique are set to keep the dose as low as reasonably achievable.

Repeated or higher-dose imaging, such as CT scanning, adds up over time, which is one reason imaging is ordered for a defined question rather than routinely.

What the image cannot say on its own

An X-ray image is one piece of evidence. Many conditions do not show on a plain X-ray, and a normal image does not rule illness out. The formal interpretation comes from a radiologist or treating clinician who reads the image together with the symptoms, history and other tests.